Detector for ferromagnetic material in an elevator well and an elevator control system operated thereby



July 19, 1966 R. MORRIS 3,261,427

DETECTOR FOR FERROMAGNETIC MATERIAL IN AN ELEVATOR WELL AND AN ELEVATORCONTROL SYSTEM OPERATED THEREBY Filed July 24, 1963 FIG. 3.

AMPLIFIER CIRCUITS H? 58 I 57 59 I I I l INVENTOR N BY swam \MQMW.

ATTORNEYS.

United States Patent 3,261,427 DETECTOR FOR FERROMAGNETIC MATERIAL IN ANELEVATOR WELL AND AN ELEVATOR CON- TROL SYSTEM OPERATED THEREBY RobertMorris, Bayside, Long Island, N.Y., assignor to Staley Elevator Company,Inc., Long Island, N.Y., a corporation of New York Filed July 24, 1963,Ser. No. 297,339 6 Claims. (Cl. 187-29) This invention relates toimprovements in detector systems for detecting magnetic material, thesystem being responsive to the presence of such material in the field ofthe detector. The invention relates also to elevator controls havingvanes along'the shaft for inductively controlling the operation of anelevator through the magnetic material detector system of thisinvention.

The expression magnetic material is used herein to designateferromagnetic material or other material which is capable of beingmagnetized and which distorts the flux :lines when brought into amagnetic field.

It is an object of the invention to provide an improvedmagneticmate-rial detector system, and more especially to provide such asystem which is more sensitive, lighter in weight, and that operates onless current, and which is effective over a wider temperature range.

Another object is to combine such a detector system in an elevatorcontrol system having vanes at spaced locations along the elevatorshaftway for inductively operating the control system. As applied to anelevator, this invention simplifies the control by using amplifiedinductively-altered signals from the vanes to operate heavy duty powerrelays, thus eliminating the necessity for the intermediate sensitivityrelays that are used on inductive controls of existing elevatorsystem-s.

Another advantage in an elevator control system that is obtained withthis invention is the increased selectivity which permits widermanufacturing tolerances, thus redu-cing the cost of the equipment; buta more important advantage of the increased sensitivity is that theresponse is faster and therefore more satisfactory. for high speedelevators. Experience has shown that with this invention the control cango from pick up to drop out of the main power relay within onlyone-sixteenth inch of vane motion relative to the elevator car.

The invention will be described as applied to an elevator control systemhaving controls that operate in response to the movement of the elevatorcar to the vicinity of the ferromagnetic metal vanes located atpredetermined locations along the shaftway; but it will be understoodthat is can be used for detecting the presence of ferromagnetic metal inother applications within the scope of the claims.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawing forming a part thereof, in which like referencecharacters indicate corresponding parts in all the views FIGURE 1 is adiagrammatic view of an elevator shaf-t with control and operatingmechanism made in accordance with this invention;

FIGURE 2 is a sectional view taken on the line 2--2 of FIGURE 1;

FIGURE 3 is a fragmentary side elevation showing the location of thedetector and amplifier assembly on top of an elevator car andillustrating the manner in which it is operated from the vane along theelevator shaft;

FIGURE 4 is a fragmentary top plan view of the apparatus shown in FIGURE3; and

FIGURE 5 is a wiring diagram [for the elevator shown in the other views.

FIGURE 1 shows an elevator car which travels up and down in a shaftway12 past various floors 14, there being four such floors illustrated inFIGURE 1.

The elevator car 10 has shoes 16 that run along tracks 18 attached toopposite side walls of the shaftway 12. There are vanes 21 and 22located along the shaftway 12 at different locations corresponding tothe floors at which the elevator is intended to stop. These vanes arecarried by brackets 24 attached to one of the rails 18 and the brackets24 are adjustable up and down along the rails to change the positions ofthe vanes 21 and 22 lengthwise of the shaft. The vanes 21 aredistributed along the shaftway 12 in a straight line and the vanes 22are distributed along the shaftiway in a straight line which is spacedfrom but parallel to the line of the vanes 21. One set of vanes controlsthe elevator when the car is moving up, and the other set of vanescontrol the elevator when the car is moving down.

A detector assembly 26 is attached to the elevator car 10 and moves upand down in the shaftway as a unit with the car. -In the diagrammaticillustration of FIGURE 1, the detector assembly 26 is located on top ofthe elevator car 10 and it is located in position to pass close to therows of vanes 21 and 22.

The elevator car 10 has a cable 31 attached to the elevator car 10 atone end and at the other end to a control means 40 which is connected toa source of power and to a hoist motor 42 which operates a cable drum 44at the head of the shaftway 12. A hoist cable 46 is connected with theelevator car 10, and this hoist cable winds on the drum 44. There isalso a brake 47 for stopping and holding the car 10, this brake 47 beingalso controlled from the control mechanism 40.

The mechanism thus far described is conventional and the diagrammaticshowing is simplified for clearer illustration. It will be understoodthat the elevator system may be an operator-controlled system or anautomatic one. The only part of the control mechanism that need beillustrated and described, for a complete understanding of thisinvention, is the part for transmitting a signal from the detectorassembly 26 to the control mechanism 40 from either the up vanes or thedown vanes.

FIGURES 3 and 4 show the detector assembly 26. This includes a housing51 with three vanes 53, 54 and 55 extending from one side of the housing51 in parallel relation with one another.

There is a primary coil 57 carried on the center vane 54. There is asecondary coil 58 carried by the vane 53; and another secondary coil 59carried by the vane 55. The coils are spaced from one another and fromadjacent vanes by sufficient space to permit the vanes 21 and 22 toenter the space between the coils as the elevator car travels up or downin the shaftway.

The primary coil 57 and the secondary coil 58 constitute a transformerand alternating current in the primary coil 57 sets up an alternatingmagnetic field in which the secondary coil 58 is located. When a vane 22is located between the coils 57 and 58, the vane 22 distorts themagnetic field and short circuits much of the field so that lines offorce reaching the secondary coil 58 are great- 1y reduced and thealternating current in the circuit of the coil 58 becomes very small.Thus a change in signal strength is produced in the circuit of thesecondary coil 58 whenever the ferromagnetic metal vane 22 moves intothe magnetic field between the primary coil 57 and the secondary coil58.

Likewise, the primary coil 57 and the secondary coil 59 form atransformer and whenever one of the vanes 21 moves into the magneticfield of this second transformer, the amount of current induced in thesecondary coil '59 is very much reduced and a change in signal strengthis thus imparted to the circuit of the secondary coil 59. It is one ofthe advantages of this invention that the coils 57, 58 and 59 may bevery small and the currents flowing in their circuits may be also verysmall.

It is a feature of the preferred embodiment of the invention that theamplifier circuit in the housing 51 is located close to the detectorcoils 58 and 59 so that the signals from these coils can be amplifiedwithout passing through any long conductors between the coils 58 and 59and the amplifying transistors. The advantage of this feature is thatthe picking up of transient currents in the conductors is avoided.Elevator cars often pass close to electrical disturbances which may belocated on the various floors of a building and if long conductors areused to transmit the relatively weak signals from the coils 58 and 59 tothe amplifiers, stray signals are picked up which adversely affect thereliability and operation of the invention. It the amplifier circuit isnot located close to the directed signal coils, then it is necessary touse larger coils and heavier current flows and signals in order toaccomplish the same purpose as this invention.

The currents to operate the amplifier in the housing 51 and to energizethe primary coil 57 are supplied by conductors in the cable 31 andcurrent to the relays in the control mechanism 40 is supplied throughother conductors 82 and 82 in the cable 31.

FIGURE is a wiring diagram illustrating the principle and the operationof the invention. The coil 58 is connected by a conductor 68 to the baseof a transistor 70. The emitter of this transistor is connected by aconductor 72 with the other side of the coil 58 and is also connectedwith a resistor 74 and with the base of a second transistor 76. Thereis, therefore, a first circuit leading from the coil 58, through theconductor 68, transistor 70, and conductor 72 back to the coil 58.

There is a second circuit leading from a conductor 78 through a diode 80to the emitter of the second transistor 76 and from the collector of thetransistor 76 through a conductor 82 in cable 31 to an actuator coil 84of a relay 86 located in control mechanism 40. The contacts 88 of therelay 86 are illustrated diagrammatically in the wiring diagram, itbeing understood that energizing of the coil 84 causes the contact 88 ofthe relay 86 to come together and thus close the relay.

This second circuit also includes a conductor 90 which joins theconductor 72, the base of transistor 76 the negative terminal ofcapacitor 96, the resistor 74 and a conductor 92, in cable 31 whichconnects with the negative side of the direct current power line 100.

There is a capacitor 96 connected across the emitter and collector ofthe first transistor 70 and connected in parallel with the diode 80 andthe bare-emitter junction of the second transistor 76.

As long as there is no magnetic material between the primary coil 57 andthe secondary coil 58, an alternating current is induced in thesecondary coil 58 and this current flows in the first circuit of theamplifier, the current being large enough to maintain the firsttransistor 78 in a conducting condition during the forward half cycleseven though this transistor 70 has a normal bias to its 011 condition,that is to a condition in which it does not conduct any current fromemitter to collector when no signal is supplied from coil 58.

When the magnetic field of the secondary coil 58 is disturbed, and thecurrent in the first circuit drops below the value which will maintainthe transistor 78 conducting, then no further current flows through thefirst transsistor 70 until the disturbance in the magnetic field of thecoil 58 is removed and the power supply in the first circuit issufficient to again cause the first transistor 70 to become conductive.

The conductor 78 is connected with the positive side of a direct currentpower line 108, and the conductor 92 is connected with the negative sideof the power line. This power supply cannot fully charge the capacitor96, however, as long'as the first transistor 70 becomes conducting oneach half cycle of its alternating current input signal because thecapacity of the capacitor 96 is made sufficient in relation to the valueof resistor 74 so that it cannot fully charge on the non-conducting halfcycle of the alternating current in the first circuit and each time thatthe transistor 70 becomes conductive on one half of its alternatingcurrent signal supply, the transistor 78 short circuits and dischargespartially the capacitor 96.

The diode is used to obtain a reverse bias on the second transistor 76while the first transistor 70 is conducting and to thus maintain thesecond transistor 76 in a cut off (non-conducting) condition so that nocurrent in the second circuit can flow to the actuating coil 84 of therelay 86-. However, when the current flow in the first circuit becomesso small that the first transistor 70 becomes non-conducting, then thecapacitor 96 is no longer short cirouited at each half cycle of thealternating current from the coil 58 and the capacitor 96 charges to asufiiciently high potential to cause a forward bias to exist on thetransistor 76 emitter base junction. This action causes the secondtransistor 76 to go to saturation and conduct current to the conductor82 in cable 31 and to the coil 84 of the relay 86 in control mechanism40, thus energizing the relay and causing it to close. This suppliespower to the conductor 62 which connects with one contact of the powerrelay 86 andthe conductor 62.

The other secondary coil 59, shown in FIGURE 5, controls a circuitsimilar to that controlled by the coil 58. Corresponding parts areindicated by th same reference characters with a prime appended.

The relay 86' operates contacts 88' to supply power to the conductor 61.The two conductors 61 and 62 from the relay circuits operate the portionof the control mechanism which control up movement and down movement,respectively, of the elevator car.

There are other diodes 106 and 106' connected between the conductors 82and 82' with the center of this dual diode connected by a conductor 108leading to the conductor 92 on the negative side of the power line 100.The purpose of this dual diode is to protect the transistors 76 and 76'from any inductive surge from the relay actuating coils 84 and 84' whenthe magnetic fields of these coils 84 and 84' are decaying. Thus thediodes 106 and 106' act as a damper.

A capacitor 110 connected between the conductors 78 and 92, incombination with a diode 112 connected in series with the conductor 78serve as a transient suppressor and the diode 112 also protects theapparatus against polarity reversal.

The invention has been illustrated and described as applied to anelevator system where the apparatus detects the presence offerromagnetic metal vanes at various locations along the shaftway, butit will be understood that the detector and amplifying equipment can beused for other situations where it is desirable to detect the presenceof magnetic material. The preferred embodiment of the invention has beenillustrated and described, but changes and modifications can be made,and some features can be used in difierent combinations withoutdeparting from the invention as defined in the claims.

What is claimed is:

1. A detector system for magnetic material including (a) a firstcircuit,

(b) means producing an alternating current in the first circuit,

(c) a coil in said first circuit in a magnetic field which is distortedby presence of magnetic material to reduce the flow of current in saidfirst circuit,

(d) a first transistor in the first circuit normally biased to benon-conducting when current in the first circuit is below a given value,

(c) a capacitor connected across the first transistor in parallel withsaid transistor,

(f) a second circuit connected with a source of power, part of thesecond circuit being connected in parallel with the first transistor andthe capacitor,

(g) a second transistor in the second circuit, at least a portion of thesecond transistor being in the part of the second circuit that isconnected in parallel with the transistor of the first circuit,

(h) a power relay for a circuit that is to be controlled,

said relay having an actuating coil in the second circuit,

(i) and means in the second circuit biasing the second transistor in anoff condition when the first transistor is conducting, the capacitorbeing of suificient capacity to avoid fully charging on any half cycleof the time that the first transistor is conducting as the result offlow of alternating current in the first circuit, and the capacitorhaving a potential, when charged more fully during a plurality of cycleswhen the first transistor is not conducting, to overcome the means inthe second circuit biasing the second transistor in an off conditionwhereby the sec-0nd circuit becomes conducting and energizes the powerrelay when the first transistor becomes non-conducting as the result ofdecrease in the alternating current in the first circuit, characterizedby the coil in the first circuit being a secondary coil of atransformer, and the means for producing an alternating current in thefirst circuit being a primary coil of the transformer that produces themagnetic field in which the secondary coil is located, and characterizedby the primary and secondary coil-s being located on an elevator carthat travels up and down in a shaftway, vanes of ferromagnetic materialat spaced locations along the shaftway in position to pass between theprimary and secondary coils as the elevator car travels past the vanes,a motor for the elevator car, and an electric circuit for the motorcontrolled by said power relay.

2. The detector described in claim 1 characterized by there being twodetector systems on the elevator car, and two sets of van-es in theshaftway, each set of vanes having its vanes in line for cooperationwith a different one of the detector systems, the power relay of one ofthe detector systems controlling operation of the elevator when the caris going up and the power relay of the other detector system controllingoperation of the elevator when the car is going down.

3. In an elevator system in which an elevator car travels up and down ina shaftway, and there is a motor for the elevator car and there areferromagnetic metal vanes located along the shaftway at different levelsin the shaftway corresponding to stations at which the elevator carstops,

(a) combination with said vanes of control means,

(b) including a detector carried by the car in position to pass close tothe vanes at the different locations as the car moves up and down in theshaftway,

(c) means for producing an electric signal in the detector as thedetector passes close to said vanes,

(d) an amplifier for the signal,

(e) a relay for controlling the supply of power to the motor,

(f) the relay having an operating coil, and

(g) a circuit in which the operating coil is located and to which theamplified signal is supplied to energize the coil to operate the relay.

4. The elevator system described in claim 3' characterized by thedetector being located at a side of the elevator car that is closeto thevanes,

(a) conductors connecting the detector with the am- (b) the amplifierbeing located immediately adjacent to the detector so that saidconductors are short to avoid pick-up of transient currents in theconductors.

5. The elevator system described in claim 3 characterized by thedetector including a transformer coil having a magnetic field that isdistorted by the vanes in the shaftway.

6. The elevator system described in claim 3 characterized by thedetector including a transformer having a primary coil and a secondarycoil spaced from one another, the space being in line with the vanes sothat the vanes pass between the coil and shield the secondary coil fromthe primary coil during travel of the car along the shaftway.

References Cited by the Examiner UNITED STATES PATENTS 2,778,978 1/1957Drew 317-149 X 2,859,402 11/1958 Schaeve 317-123 2,874,806 2/1959Oplinger 187-29 3,199,630 8/1965 Engle et al. 187-29 ORIS L. RADER,Primary Examiner.

T. LYNCH, Assistant Examiner.

1. A DETECTOR SYSTEM FOR MAGNETIC MATERIAL INCLUDING (A) A FIRSTCIRCUIT, (B) MEANS PRODUCING AN ALTERNATING CURRENT IN THE FIRSTCIRCUIT, (C) A COIL IN SAID FIRST CIRCUIT IN A MAGNETIC FIELD WHICH ISDISTORTED BY PRESENCE OF MAGNETIC MATERIAL TO REDUCE THE FLOW OF CURRENTIN SAID FIRST CIRCUIT, (D) A FIRST TRANSISTOR IN THE FIRST CIRCUITNORMALLY BIASED TO BE NON-CONDUCTING WHEN CURRENT IN THE FIRST CIRCUITIS BELOW A GIVEN VALUE, (E) A CAPACITOR CONNECTED ACROSS THE FIRSTTRANSISTOR IN PARALLEL WITH SAID TRANSISTOR, (F) A SECOND CIRCUITCONNECTED WITH A SOURCE OF POWER, PART OF THE SECOND CIRCUIT BEINGCONNECTED IN PARALLEL WITH THE FIRST TRANSISTOR AND THE CAPACITOR, (G) ASECOND TRANSISTOR IN THE SECOND CIRCUIT, AT LEAST A PORTION OF THESECOND TRANSISTOR BEING IN THE PART OF THE SECOND CIRCUIT THAT ISCONNECTED IN PARALLEL WITH THE TRANSISTOR OF THE FIRST CIRCUIT, (H) APOWER RELAY FOR A CIRCUIT THAT IS TO BE CONTROLLED, SAID RELAY HAVING ANACTUATING COIL IN THE SECOND CIRCUIT, (I) AND MEANS IN THE SECONDCIRCUIT BIASING THE SECOND TRANSISTOR IN AN OFF CONDITION WHEN THE FIRSTTRANSISTOR IS CONDUCTING, THE CAPACITOR BEING OF SUFFICIENT CAPACITY TOAVOID FULLY CHARGING ON ANY HALF CYCLE OF THE TIME THAT THE FIRSTTRANSISTOR IS CONDUCTING AS THE RESULT OF FLOW OF ALTERNATING CURRENT INTHE FIRST CIRCUIT, AND THE CAPACITOR HAVING A POTENTIAL, WHEN CHARGEDMORE FULLY DURING A PLURALITY OF CYCLES WHEN THE FIRST TRANSISTOR IS NOTCONDUCTING, TO OVERCOME THE MEANS IN THE SECOND CIRCUIT BIASING THESECOND TRANSISTOR BECOMES AN OFF CONDITION WHEREBY THE SECOND CIRCUITBECOMES CONDUCTING AND ENERGIZES THE POWER RELAY WHEN THE FIRSTTRANSISTOR BECOMES NON-CONDUCTING AS THE RESULT OF DECREASE IN THEALTERNATING CURRENT IN THE FIRST CIRCUIT CUIT, CHARACTERIZED BY THE COILIN THE FIRST CIRCUIT BEING A SECONDARY COIL OF A TRANSFORMER, AND THEMEANS FOR PRODUCING AN ALTERNATING CURRENT IN THE FIRST CIRCUIT BEING APRIMARY COIL OF THE TRANSFORMER THAT PRODUCES THE MAGNETIC FIELD INWHICH THE SECONDARY COIL IS LOCATED, AND CHARACTERIZED BY THE PRIMARYAND SECONDARY COILS BEING LOCATED ON AN ELEVATOR CAR THAT TRAVELS UP ANDDOWN IN A SHAFTWAY, VANES OF FERROMAGNETIC MATERIAL AT SPACED LOCATIONSALONG THE SHAFTWAY IN POSITION TO PASS BETWEEN THE PRIMARY AND SECONDARYCOILS AT THE ELEVATOR CAR TRAVELS PAST THE VANES, A MOTOR FOR THEELEVATOR CAR, AND AN ELECTRIC CIRCUIT FOR THE MOTOR CONTROLLED BY SAIDPOWER RELAY.